Analysis of the spatial and temporal trends of precipitation and temperature are pertinent for future development and sustainable management of water resources in a given region. In this paper, we present a study concerning the climatic behavior of two principal observables Variables, viz. monthly temperature (maximum and minimum) and mean precipitations obtained from the measurements carried out in 60 Iranian meteorological stations for 40 years from 1969 to 2008. The Mann-Kendall test was used to detect the significant trends.Results showed that during summer and autumn, the precipitation had a negative trend (at 5% significant level) in the south-eastern parts of Iran and this trend is less during spring, but no special trend was observed in winter. The minimum and the maximum temperatures did not have any particular trend in winter. Spring was accompanied by an increase in positive trend in the maximum temperatures in the south-west and north-east, while the minimum temperature only limited in the south-west parts. Positive and negative trends of the minimum temperature were very dispersed during the summer. The maximum temperatures had a negative trend in the north-west and no positive trend was observed at 5% significant level. During autumn, the temperatures indices had positive and negative trends with a wide range of dispersion.

Alijani, B. and Ghavidel Rahimi, Y. Comparison and prediction of the temperature variations of Tabriz with the global temperature anomalies through the use of regression and artificial neural network methods, Geo. Develop., 2005; 6: 21-38. (In Persian)

Frei, T. and Gassner, E. Climate change and its impact on birch pollen quantities and the start of the pollen season an example from Switzerland for the period 1969-2006, Int. J. Biometeorol., 2008; 52: 667-674.

IPCC, Climate change. The scientific basis: summary for policymakers, Part of the Working Group I Contribution to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK, 2001; 260 P.